Measured-service telephone system



Jan. 22 1924.

T. G. MARTIN MEASURED SERVICE TELEPHONE SYSTEM Filed Nov. 10 1920 InLrBnZDr Patentd. 22, 19%.

TES

NT OFFICE..

TALBOT G. TIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC COM- PAINT, OI CHICAGO, ILLINOIS, A. CORPORATION OF ILLINOIS. I

' MEASURED-SERVICE TELEPHONE SYSTEM.

Application med November 10, 1920. Serial No. 428,155.

To all whom it may comm:

Be it known that I, TALBOT G. MARTIN, a citizen of the United States of America, and a resident of Chicago, Cook County, and State of Illinois, have invented certain new and useful Improvements in Measured-Service Telephone Systems, of which the following is a specification.

- The present invention relates in general to measured service telephone systems, and more particularly to automatic systems in which the subscnbers meters are located at the exchange. The object of the invention is to provide certain improvements in the meter control circuits, whereby a system of this kind is rendered more eflicient in ractice.

The improvements referred to wi 1 be described fully hereinafter with reference to the accompanying drawing, in which there is shown sufiicient of the apparatus in an automatic telephone system to enable the invention to be explained andunderstood.

Referring to the drawing, the layout of the system shown therein is as follows: The telep one A, havin the usual transmitter, recelver, bell, and c ling device, is connected to the line conductors 2 and 3 in the usual manner. At the exchange the line termi-- nates in the rotary line switch indicated by reference character G, which is of well known construction .and which is provided for the purpose of extending) the line, responsive to the removal of t e receiver at the telephone, to a trunk line terminating in an idle selector switch. One such trunk line, comprising conductors 4:1, 42, and 43, is shown extending to the selector D. Selector switches, as is well known, have the function of extending calling lines to idle connector switches in desired hundred groups, and there may be only one selector or a pluralit in serial relation, in any given connection, epending on the size of the system.

As shown herein one of the trunk lines to which the selector D has access extends to the connector H, which is operable to complete connection to any one of a group of 100 lines, one of which is the line extending to the telephone station A. Line selector, and connector switches are well known in the art and, sin% they have nothing in articular to do with the invention, most 0? the circuit details have for simuse The meters or call registers, such as the meter M associated with the station A, are located at any preferred place in the exchange as, for example, in a cabinet, or they may be mounted on the switchboard adjacent to the line switches. Themeters are operated by relays in the selector trunks,

such as relays 28, and 29, in a manner which will now be explained.

Suppose the subscriber at station vA deslres to call the subscriber at station A. in WhlCh case it will .be necessary to actuate the meter M at the proper time to register the call. Upon the removal of the receiver at station A a circuit is completed over lme conductors 2 and 3 for the line relay 5 of the line swltch C. Upon energizing, the line rel'ay 5 closes at its armature 7 a circult whlch 1ncludes the switching relay 4 and the stepping magnet 6 in series, the cir cult also extending throu h the meter M, indiv dual toline switch to battery. The meter being marginall adjusted does not operate at this time. t the same time that the circuit of relay 4 is closed the line relay, by means of its armature 8, connects the test w1per 22 to the circuit at a point midway between the relay and the stepping magnet. The operation now, depends upon whether the trunk line, with which the wipers of the line switch C are associated, is busy or is not busy. If the trunk line 1s busy the test contact with which the test wiper 22 is in engagement will be grounded. and as a result the switching relay 4 will be short circuited and the stepping magnet 6, being supplied with direct ground by way of the test wiper, will operate as a buzzer to advance the switch wipers step by step in search of an idle trunk line. It ma be assumed, however, that when the cal is initiated the wipers of the line switch C are standing upon the bank contacts shown in the drawing, and it ma be assumed fun thermore that the trunk line extending from these bank contacts is idle; Under these circumstances the test contact 25 will have no ground potential on it and when the receiver is removed the energization of line relay 5 is followed immediately by the energization of the switching relay 4. It may be stated at this point that the resistance of the switching relay 4 is very high so as to prevent the operation of the stepping magnet at this Relay 4, upon energizing, grounds the test wiper 22 at its armature 11, and at its armatures 9 and 10 disconnects the line conductors 2 and 3 from the winding of the line relay 5 and from ground, respectively, and extends them by wa of Wipers 21 and 23, bank contacts 24 and 26, and conductors 41 and 43 to the line relay (not shown? of the first selector D. When ground is p aced upon test wiper 22 a circuit is closed for relay 28 by way of test contact 25, conductor 39, normally closed contact springs controlled by armature 33, conductor 38, armature 31 and its resting contact, and through the winding of relay 28 to battery. Upon energizing, relay 28 opens the shunt around the top winding of relay 29 at armature 35, prepares a circuit for the booster battery B at armature 34, and at armature 33 connects conductor 39 to the release trunk conductor 42 by way of the normally closed oont'act springs controlled by armature 32 of relay 29.

When the calling line is extended to the selector D as previously explained, the line and release relays of the selector are energized in the usual manner, and the latter rela connects ground to the release trunk conductor 42, thus establishing a holding circuit for relay 4 as follows: grounded release trunk conductor 42, normally closed contact springs controlled by armature 32, armature 33 and its working contact, conductor 39, test contact 25, test wiper 22, armature 11 and its working contact, winding of relay 4, and through the winding of magnet 6 to battery. The above described holding circuit is completed before the slow acting relay 5 has time to fall back, and it will be seen therefore that relay 4 will be maintained energized.

So far the circuits have been described in considerable detail in order to make the invention perfectly clear, but since the remainder of the equipment to be described in the connection is old, this will no longer be necessary. It will sufiice to say that the subscriber at station A will now operate his calling device in accordance with the digits in the number assi ed to station A, whereupon the selector fi and a connector switch, assumed to be the connector H, are operated to complete the desired connection and signal the called subscriber.

Upon the removal of the called partys receiver the back bridge relay 59 of the connector is energized, this rela having the well known function of reversmg the direction of current flow in the calling line. This brings us to the consideration of the means for actuatin the meter M to register the call. The re ay 29 in the trunk line extending to selector D is an electro-polarized relay, which has an inefiicient polarizing winding of high resistance throu h which current flows from the grounded re ease trunk conwindin ductor 42, while the trunk is in use. This winding and the top winding, which is in series with conductor 41, are in opposition during the establishment of the connection and until the called subscriber answers, relevy 29 therefore remaining inoperative.

hen the called subscriber answers, and current is reversed in the calling line, the of relay 29 assist each other and the sai relay is o erated, with the result that armature 31 break ing relay 28, while armature 32 .operates to connect the booster'battery B to th holding circuit at its workin contact, at the same time disconnecting t e release trunk conductor. A new circuit is thereby established for meter M as follows: ground at G, booster battery B, resistance R, working contact of armature 34 and the said armature, armature 32 and its working contact, armature 33 and its working contact, test contact 25, test wiper 22, armature 11 and its working contact, private normal conductor 1, and the winding of the operating magnet of meter M to battery. Since the booster battery B has its negative pole connected to ground, whereas the exchange batter has its positive pole connected to ground, t e two will now assist each other. The 'meter magnet thereupon attracts its armature. A moment later the slow acting relay 28 releases; u on so doing it reconnects the release trun conductor 42 to the holdin circuit at the resting contact controlled y armature 33, and disconnects the booster battery by opening the working contact of the same armature. The booster battery is disconnected at armature 34 also, to guard against its being momentarily reconnected to the release trunk when armature 32 of relay 29 is released at the end of the connection. At armature 35 the top winding of relay 29 is short circuited so as not to interfere with the talking circuit. The armature of the magnet of meter M having been attracted when the booster battery was introduced into the circuit will be held energized by the excha e battery until the connection is releas dd, which takes place, in the usual manner, when the receiver is replaced at station A whereupon the armature is retracted to adlilmnoe the number wheels to register the ca The foregoing describes the usual 0 eration in registering successful calls. it is understood, of course, that if the called line is busy, the connector in use will be prevented from completing the connection, and no call will be registered, and the same thing is true if the called subscriber fails to answer, for in neither case is the current reversed in the first selector trunk and relay 29 there fore is not operated.

Having described m invention, what I consider to be new an desire to have pros the circuit of slow actanemia tested by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a subscribers line, a rotary line switch for extending said line when calling, said switch having two line wipers and a test wiper, a holding circuit for said switch including said test wiper, an individual meter for said line connected to said circuit, and means for momentarily increasing the current flow in said holding circuit to operate said meter, said means comprising a slow acting relay energized over said holding circuit, and a polar relay for opening the circuit of said slow relay.

2. In a telephone system, a subscribers line, a rotary line switch for extending said line when calling, said switch having two line wipers and a test wiper, a holding circuit for said switch including said test wiper, an individual meter for said line connected to said circuit, a booster battery, and means for connecting said battery in the holding circuit to operate said meter.

3. In a telephone system, a calling subscribers line, means including an individual line switch and a first selector switch for extending said line to a called line, a trunk line between the said line and selector switches, a holdin circuit for the line switch including a thir conductor of said trunk line, a meter connected to the holding circuit and irresponsive to normal current flow therein, and a polar relay in said trunk line for increasing the current flow in said holding circuit to operate said meter.

4. In a telephone system, a calling subscribers line, means including an individual line switch and a first selector switch for extending said line to a called line, a trunk line between the said line and selector switches, a holding circuit for the line switch including a third conductor of said trunk line, a meter connected to the holding circuit and irresponsive to normal current flow therein, and means in said trunk line operated when the called part answers to increase the current flow in sai trunk line to operate said meter.

5. In a telephone system, a calling subscribers line, means including an individual line switch and a first selector switch for extending said line to a called line, a trunk line between the said line and selector switches, a

holding circuit for the line switch including a third conductor of said trunk line, a meter connected to the holding circuit and irresponsive to normal current flow therein, a booster battery, and means in said trunk line for connecting said battery in said holding circuit tooperate said meter.

6. In a telephone system, a calling subscribers line, means including an individual line switch and a first selector switch for extending said line to a called line, atrunk line between the said line and selector switches, a holding circuit for the line switch including a third conductor of said trunk line, a meter connected to the holding circuit and irresponsive to normal current flow therein, a booster battery, and a rela in said trunk line operated when the calls part answers to connect said battery in the ho ding circuit to operate said meter.

7. In a telephone system, a calling subscribers line, means including an individual line switch and a selector switch for extending said line to a called line, a trunk line between the said line and selector switches, a holdin circuit for the line switch including a thir conductor of said trunk line, a meter connected to the holding circuit and irresponsive to normal current flow therein, a final connector switch constituting part of said first means, means in said connector for reversing the direction of current flow in the line conductors of said trunk line when the called party answers, a booster battery, and a polar relay responsive to the said current reversal to connect said battery in the holding circuit to operate said meter.

8. In a telephone system, a calling line, a meter for said line, a trunk line and a series of automatic switches for extending a connection from said line to a called line, a relay in said trunk line operated during the progress of the call to prepare an operating circuit for said meter, and a second relay operated when the call is answered to complete said meter circuit and to deenergize said first relay.

9. In a telephone system, for said line, a trunk line, means including a series of automatic switches for extendin connections from said line over said tru line, a pair of relays normally connected to one conductor of said trunk line, one of said relays responsive during the progress of a call to cause a role. to be included in series with another con uctor of said trunk line' and to prepare an operating circuit for said meter, said other relay responsive when a call is answered to disconnect said first relay and to complete an operatin circuit for said meter.

Signed by me at hica 0, Cook County, Illinois, this 28th dial of ct., 1920.

T BOT G. MARTIN.

a line, a meter.

second winding of the other 

